Something I thought of when I was studying engineering at Uni (I dropped out) was to fit a small device onto the accelerator cable of a car that can apply varying degrees of tension to the pedal. This device would be moderated by the computer in the car to "condition" the driver to adopt a more fuel-efficient driving style. If you drive in a non-fuel efficient manner, there would be more "drag" on the pedal, thus req…
From the article: The [Nissan] Eco Pedal is designed to provide a "counter push-back control mechanism" if it senses "excess pressure" on the accelerator. In other words, it does not like lead foots. The premise of this new technology, which Nissan says is a "world first," is to help the driver get an immediate sense that he or she "could be using more fuel than required."